Tag: Papio anubis

DISCUSSION(6)

Expression of mRNA of PKA subunits did not differ in nondecidualized and decidualized cells in either the baboon or the human. This confirms a recent study showing that all four isoforms were present in human endometrial stromal cells, with no difference in the mRNA expression of the isoforms between decidualized and nondecidualized cells. Even the mRNA for catalytic subunits did not change. In contrast, Knutsen et al. demonstrated that a mouse Sertoli cell line expressed the RIa, RIIa, and RIIp subunits and that RIIp was up-regulated by cAMP, reaching maximal levels after 12 h of stimulation. In primary cultures of rat Sertoli cells, mRNAs for RIa, RIIa, and RIIp are regulated with cAMP treatment whereas in the TM4 cell line, none of the various PKA subunit mRNAs were regulated by cAMP. In ovarian follicular cells, RIa protein levels increase while mRNA levels do not change in response to elevated cAMP levels. Thus, it appears that PKA regulatory subunits are differentially regulated depending on the cell type. buy ortho tri-cyclen

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Several reports have indicated that stimulation of the cAMP signaling pathway is an important factor in deci-dualizing stromal cells. The mechanism by which this is accomplished, however, requires further investigation. Our studies suggest that decidualization, as assessed by IGFBP-1 and prolactin induction, requires several intermediate steps associated with the cAMP signaling pathway. The response to cAMP was not immediate; it required 48 h of stimulation.

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DISCUSSION(4)

The function of IGFBP-1 produced by the decidua is poorly understood. The IGFBPs either can enhance or inhibit insulin-like growth factor (IGF) action or could act independently of IGFs and bind to integrins through the IGFBP-1 RGD sequence. The involvement of IGFBP-1 in controlling trophoblast invasion has been suggested but remains unresolved. One possible mechanism supporting this concept involves the interaction of IGFBP-1 with in-tegrins. It has been shown that mouse primary trophoblast cells when cultured on extracellular matrix proteins appear to interact with fibronectin exclusively through the RGD recognition site. IGFBP-1 contains the RGD tripeptide sequence, which can bind to the a5p! integrin receptor. ventolin inhaler

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One possible role for the appearance of aSMA, other than initiating changes in cell shape, may be to decrease the proliferation process in these cells in preparation for differentiation. It has been shown that induction of aSMA by transforming growth factor p in smooth muscle inhibits proliferation, thus maintaining the cell in its contractile state. Also, changes in actin or actin-binding proteins appear to be important for cellular differentiation of granulosa cells. It would be interesting to determine whether the expression of aSMA is necessary in order for stromal cells to decidualize or whether this process is an independent phenomenon unrelated to the decidualization process. buy diabetes drugs

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DISCUSSION(2)

Cytoskeletal proteins are important in mitosis, cell growth, and changes in cell shape and also for the regulation of protein secretion. Alpha SMA is an important filamentous protein associated with the cytoskeleton. In the baboon, aSMA is absent in the stromal fibroblasts of the endometrium throughout the menstrual cycle but becomes evident as early as Day 14 of pregnancy and Day 18 of simulated pregnancy. Between Days 32 and 40 of pregnancy, the number of positively stained stromal fibroblasts decreases, particularly around the implantation site, and by Days 50-60 this staining disappears. We have shown in our in vitro system that cells begin to produce aSMA shortly after they are put into culture. birth control pills

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This is the first report that describes in vitro deciduali-zation in a nonhuman primate. We have demonstrated that baboon stromal cells require dbcAMP in addition to hormones to produce high levels of IGFBP-1.

Evidence presented in this study suggests that the processes of decidualization in the human and baboon involve similar mechanisms. Both human and baboon stromal cells expressed aSMA in culture and, in response to hormones and dbcAMP, high levels of IGFBP-1. Furthermore, stromal cells from the human and baboon were responsive to shortterm dbcAMP treatment after pretreatment with hormones. Within each species, decidualized and nondecidualized cells did not differ in their expression of PKA regulatory subunit isoforms. Thus, these two species appear to possess similar metabolic pathways necessary for decidualization, but the process of decidualization differs in its sensitivity or degree of responsiveness to external stimuli. Human de-cidualizing stromal cells generally produced higher levels of prolactin and IGFBP-1 than baboon cells and were more responsive to dbcAMP.

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RESULTS(5)Short-Term dbcAMP Treatment

Human and baboon stromal cells were pretreated with hormones for 2, 12, or 17 days, and dbcAMP was added for the last 48 h of each time point. This was done in order to determine whether long- or short-term treatment with dbcAMP was required for decidualization and IGFBP-1 expression. In human stromal cells, levels of IGFBP-1 significantly increased in response to 48 h of dbcAMP treatment at both 2 and 12 days (Fig. 5B; p < 0.01). In baboon cells, a significant increase in IGFBP-1 was observed in response to dbcAMP only after 17 days of hormone pretreatment (Fig. 5A; p < 0.01). The quantity of IGFBP-1 produced by both human and baboon cells in response to short-term dbcAMP treatment (Fig. 5) was much lower than the levels obtained after long-term treatment with dbcAMP (Fig. 3). These data show that dbcAMP is able to act in a short-term manner to induce IGFBP-1 production when cells are pretreated with hormones. Furthermore, it is evident that cells at the initial stages of hormone treatment differ in their responsiveness to dbcAMP from cells subjected to long-term hormone pretreatment. buy levaquin online

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